The following comment was raised as part of the discussion on bug #4874, and is raised here as an enhancement request so that it is not lost when 4874 is closed.

For the future: it seems unsatisfactory that the only way of constructing a
NOTATION is from a literal string, and that there is no way of processing a
NOTATION other than converting it to a string. This makes it impossible for the
user to determine, for example, what namespace a NOTATION is in, or to ensure
that this namespace is declared when an attribute of type NOTATION is written
to the result tree. I suggest that we should allow casting between QName and
NOTATION in both directions, with the obvious semantics, making operations
defined on QNames available for constructing and deconstructing NOTATIONs.